Radiation damage effects in boron nitride mask membranes subjected to x-ray exposures

The effects of radiation damage with 1 to 3 keV x-rays on hydrogenated boron nitride films prepared by LPCVD have been investigated. It is shown that both the surface and bulk film properties of these materials are modified and may potentially limit the use of this material as a membrane in an x-ray mask structure. Specifically, it is shown that growths will form on exposed boron nitride surfaces irradiated in oxygen-containing ambients; optical transmission of irradiated films will degrade with the cumulative absorbed dose; the tensile stress of an x-ray mask membrane will decrease and introduce pattern distortions depending upon the irradiation dose/flux and exposure geometries. A model to evaluate the observed pattern distortions and a mechanism to explain the observed stress changes of the hydrogenated boron nitride films are proposed.